Gas turbine combustors generally use a number of fuel nozzles positioned about an end cover. Given the potential for large temperature variations among the various internal passages of the fuel nozzles, particularly during transient operations, differing axial thermal growth of the passages may be a design issue. For example, different passages may have fluids of differing temperatures therein or different passages may be constructed of materials with varying coefficients of thermal expansion. Moreover, these passages generally may take the form of concentric tubing. As such, these concentric tubes should have support and vibration damping.
Known fuel nozzles generally have used bellows or piston rings as seals between the concentric tubes. The use of bellows, however, is somewhat costly and may have durability issues. Likewise, the use of piston rings may provide for considerable leakage therethrough. High leakage variation thus may result, particularly between two passages with a high delta pressure thereacross and may lead to undesirable combustion characteristics.
Lip seals have been found to provide improved sealing performance as compared to known piston rings. The lip seals may be positioned and captured at one end about a flange tube end welded onto the end of a sleeve assembly tube and captured at a second end via a counter bore in the fuel nozzle body. Although this method may be effective, subsequent seals must be of an alternate reduced size so as to allow assembly and capture of the seal in both directions. For fuel nozzles requiring multiple seals, there may not be enough space in the radial direction to utilize this method for all required seals.
There is therefore a desire for an improved method of mounting lip seals onto fuel nozzle tubes and adequately capturing them in place. The use of lip seals instead of piston rings should improve the sealing between various nozzle circuits and subsequently improve overall emissions and performance.